
©Silberschatz, Korth and Sudarshan2.9Database System Concepts - 5th Edition, Oct 5, 2006
Database
Database
A database consists of multiple relations
Information about an enterprise is broken up into parts, with each relation
storing one part of the information
account : stores information about accounts
depositor : stores information about which customer
owns which account
customer : stores information about customers
Storing all information as a single relation such as
bank(account_number, balance, customer_name, ..)
results in
repetition of information
e.g.,if two customers own an account (What gets repeated?)
the need for null values
e.g., to represent a customer without an account
Normalization theory (Chapter 7) deals with how to design relational schemas